1. Field of the Invention
The present invention relates to protecting the environment from waste gases and fluids produced by leakage in reciprocating rod-type fluid displacement arrangements such as those of pumps, compressors, and other devices where the potential exists for leakage of a gas or liquid about a rod which reciprocates through a casing, pipe, housing, or the like.
2. Description of Related Art
Reciprocating rod arrangements are commonly utilized in connection with such devices as pumps and compressors acting on toxic gases and liquids; for example, oil well pumping units, where a packing gland system or other form of seal or packing is utilized to prevent leakage from passing out of the arrangement from around the reciprocating rod. However, no matter how effective a seal or packing arrangement may be when new, ultimately wear on the packing or seal occurs due to the reciprocating action of the rod through the packing or seal, and with wear, leakage of vapors and/or liquids through the packing or seal occurs. Furthermore, while the extent of leakage may not be sufficient to cause shutting down of the equipment to replace the seal or packing due to the associated reduction in production or the potential for damage to the associated equipment, even small amounts of vapor and liquid leakage into the surrounding environment creates a measurable amount of pollution and a potential hazard, especially where the device is utilized within a building.
In the case of wells that are located in metropolitan areas or offshore, environment concerns are particularly acute, so that frequent servicing of the packing or seal around the reciprocating rod becomes necessary to prevent leakage that would, otherwise, be considered inconsequential from an operational or economic standpoint. Thus, while it is known to provide stuffing boxes with leakage detectors (see Truman, et al. U.S. Patent No. 3,276,246), such arrangements merely serve to terminate operation once excessive leakage occurs, and do not deal with the problem of leakage occurring under circumstances where, but for environmental/safety concerns, there is no need to terminate operation.
In U.S. Patent No. 4,530,397 to Calhoun, an oil saving apparatus for use with a well pump polish rod is disclosed for conserving oil which may leak from the stuffing box of an oil well pump polish rod by passing along the polish rod when the stuffing box packing wears or dries out. In accordance with this patent, a housing is welded onto the top of a conventional stuffing box of a well head fitting. The housing contains an auxiliary packing, a fluid leakage collection chamber and discharge ducts. Fluid leakage collected by the collection chamber and leakage fluid which may pass through the collection chamber into the auxiliary packing are drained by the discharge ducts into a collection receptacle. While such an apparatus may conserve an amount of oil that would otherwise be lost due to leakage, since the auxiliary packing will be as prone to wear as the conventional packing of the stuffing box of the well head, this apparatus will not effectively deal with the problem of protecting the environment from waste and other toxic gases passing out along the shaft into the environment, nor will it totally eliminate the leakage of fluid into the environment.
Johnston U.S. Patent No. 3,270,810 reflects the need to prevent damage to vegetation and property adjacent a well due to the discharge of oil, salt water, and gas into the environment, but only to the extent that such may be sprayed into the atmosphere and carried by the winds over a large area due to a "blowout," i.e., an essentially total failure of the seal. The polish rod protector and blow deflector of Johnston is comprised of a bonnet into which any blowby oil or water which may occur due to failure of the stuffing box will be collected and conveyed, via a discharge conduit, to the earth immediately adjacent the well, rather than sprayed over surrounding vegetation and into the atmosphere. Furthermore, a bellows is affixed to the top of the bonnet and is clamped to the polish rod so as to cause the bellows to communicate with the interior of the bonnet and to expand and contract with reciprocation of the polish rod. The bellows serves the purpose of protecting the polish rod from blowing dust and dirt, and results in air breathing in and out of the bonnet, via the discharge conduit, as the bellows is reciprocated up and down with the polish rod.
Thus, on the one hand, the presence of a discharge conduit makes the Johnston device incapable of achieving the current demand for increased environmental protection; and, on the other hand, if the discharge conduit were merely to be eliminated, air would no longer be able to breathe in and out of the bonnet, so that extension of the bellows would produce a suction effect that would increase the tendency for gas and oil to leak past the packings, and there would be no means to vent the bonnet of accumulated gases and liquids which are collected in it.
A safety hood apparatus for drilling heads is disclosed in McHenry U.S. Patent No. 3,322,198 which is designed for enclosing rotating assemblies, such as blowout preventers and strippers of oil well drilling rigs to exhaust or remove leakage materials emanating from them. The lower portion of the hood is securely fastened to the lower section of a rotating head directly above the flow line, while the upper portion of the hood extends above the exposed portion of the rotating assembly drive bushings or rings and has a hole diameter at that point sufficient to permit withdrawal of the preventer and stripper from the hood without removing the hood. Furthermore, a suction pump is coupled to the hood and flow line, via a suitable conduit, to withdraw any dispersals or suspensions of gas, air, dust cuttings, and so forth, from the atmosphere confined by the hood, as a result of leakage about the stripper, bonnet, or other parts of the rotating assembly, and so as to exhaust such materials to the flow line or overflow outlet. To ensure proper operation of the pump, the hole in the upper portion of the hood does not form a tight seal and operates to allow sufficient air to flow into the hood, which results in a slight positive pressure being maintained inwardly of the hood at its upper portion.
However, the safety hood apparatus of McHenry is not suitable for use in reciprocating rod fluid displacement arrangements. Furthermore, on the one hand, if an inadequate level of vacuum is not maintained within the hood, the portions at which air is able to flow into the hood can serve as sites at which leakage gases and liquids can escape, while, on the other hand, if a relatively high vacuum is maintained within the hood, the vacuum drawn by the pump will undesirably foster leakage.
Thus, there is still a need for an environmental leakage protector for reciprocating rod fluid displacement arrangements, such as pumps, pumping units, and compressors, which will effectively protect the environment from gases and liquids produced by leakage and reciprocating rod action devices without affecting operation or increasing the propensity toward leakage.